Ultrasonic sensors are already prior art and can be mounted in known manner in the front region and in the rear region of a motor vehicle, namely for instance at the respective bumpers. The ultrasonic sensors are assigned to driver assistance devices and provide information about the environment of the vehicle, and more precisely about the distances between the motor vehicle, on the one hand, and the obstacles present in its environment, on the other hand. Driver assistance devices in this connection may for instance be parking assistance systems, systems for dead angle monitoring, headway control systems, braking assistance systems, collision detection systems, and the like.
It is already prior art that such ultrasonic sensors are built into bumpers in uncovered arrangement. This means that the ultrasonic sensors are arranged in open recesses or through-openings in the bumper and are visible on the outside. Here the pot-shaped membrane of the ultrasonic sensor—the so-called aluminum pot—extends through the through-opening of the bumper so that a front side or a front surface of the membrane is flush with the outer surface of the bumper. The front side of the membrane here may be varnished for instance in the color of the bumper. For vibration isolation of the membrane from the bumper commonly a decoupling ring made from a soft material is used, which is arranged around the membrane and fits around an outer circumference of the pot-shaped membrane. This decoupling ring is for instance formed from silicon.